河流沉积相土层结构对砂土液化的影响研究  

Effect of soil layer structure with fluvial sedimentary facies on sand liquefaction

作　　者：王伟[1] 齐亚坤 王浩宇 李金宇 张晓庆 沈超[1] 冯伟栋[2] Wang Wei;Qi Yakun;Wang Haoyu;Li Jinyu;Zhang Xiaoqing;Shen Chao;Feng Weidong(Institute of Disaster Prevention,Hebei Sanhe 065201,China;Anhui Earthquake Agency,Hefei 230031,China)

机构地区：[1]防灾科技学院,中国河北三河065201 [2]安徽省地震局,中国合肥230031

出　　处：《地震学报》2022年第4期665-676,共12页Acta Seismologica Sinica

基　　金：中央高校基本科研业务费(ZY20180107);中国地震局地震科技星火计划(XH19068Y)共同资助。

摘　　要：目前相关规范主要依据工程场地单点的测试数据进行砂土液化判别,而实际的三维土层结构可能非常复杂。研究土层结构对砂土液化的影响机制,有利于提高砂土液化判别结果准确度。分析2008年5月28日发生的松原MS地震和2010—2011年新西兰坎特伯雷地震序列中砂土液化点的分布,结果显示:砂土液化点主要位于高弯度河流的沉积相地层,凹岸侧蚀、凸岸沉积形成的边滩具有典型的二元结构,其顶部分布的黏土类不透水层有利于下伏饱和粉细砂等易液化土层的超孔隙水压累积;而辫状河流沉积相中,上覆黏土类不透水层间断分布特征明显。针对河流不同沉积相的土层结构建立简化场地模型,使用FLAC3D进行砂土液化数值模拟,揭示出不同土层结构中超孔隙水压力的累积、消散和渗流过程机制,结果表明,河流沉积相土层结构对砂土液化场点的分布和地表变形具有显著影响。在合理的工程地质分区基础上,现有的液化判别方法有必要考虑场地的土层结构的影响。The sand liquefaction potential is evaluated with the in-situ test data of one single borehole in the relative codes,however,the real three-dimensional structure of the engineering site is very complex.It is helpful to increase the accuracy of the sand liquefaction evaluation by studying the effect of the soil layer structure on the liquefaction.By analyzing the distribution of the sites of the sand liquefaction manifestation caused in Songyuan MS5.7 earthquake on the 28May,2008 and the 2010-2011 Canterbury earthquake sequence,it is discovered that most of the sites are located on the inside bend of the meandering river.The dualstructure exists in the point bar formed by the lateral erosion of the outside bend and the deposition of the inside bend.The impermeable(including weakly permeable)clay layer is covered on top of the saturated fine sand,which is easy to cause the accumulation of the excess pore pressure.The discontinuous distribution of the impermeable clay layer is obvious in the braided fluvial facies.The simplified model is built for soil layer structures with the different fluvial sedimentary facies.The FLAC3D software is used to study the mechanism of the accumulation and dissipation of the pore pressure,and the seepage flow process.The distribution of sand liquefaction manifestation and the ground surface deformation is highly affected by the the soil layer structure with the fluvial sedimentary facies.It is necessary to consider the influence of the soil layer structure in the sand liquefaction evaluation methods on the basis of engineering geological zoning.

关 键 词：河流相沉积 土层结构 砂土液化 数值模拟 二元结构 

分 类 号：P315.9[天文地球—地震学] TU42[天文地球—固体地球物理学]